Airfoil construction



Sept 21,1943- G. A. WEINGARTNER 2,329,962

AIRFOIL CONSTRUCTION Filed Aug. 9, 1941 ma i wmf @f o .mw Q od atented Sept. 2i, i943 2,329,962 intron. coNs'rRUc'rroN Gerald A. Wengartner, Buialo, N. Y., assigner to Bell Aircraft Corporatiomuffalo, N. Y.

7 Claims.

This invention relates to airfoil constructions, and more particularly to improvements in airfoil framing structures designed to simplify manufacturing processes in connection therewith and to provide a simplified and rugged and otherwise improved product. l

In the drawing:

Fig. 1 is a fragmentary plan of an airfoil structure, such as an airplane .elevator or rudder, or the like, of the invention;

Fig. 2 is a fragmentary section, on an enlarged scale, taken substantially along line II--II of Fig. 1;

Fig. 3 is a fragmentary section taken substantially along line III-III of Fig. l; and

Fig. 4 is a fragmentary section taken at -IV-IV of Fig. 2. L

The drawing illustrates the invention as in connection with an airplane rudder, elevator,

trim tab, or the like, wherein an airfoil framing t720 structure is fabricated to include a series of parallel rib units I0 which join at their rear end portions with a trailing edge piece l2. The trailing edge. piece-I2 is of sheet metalformed into U-shaped sectional form. The rib units I0 are each fabricated of paired 'rib elements I4--I6 which are formedfof similar metal stock of generally T-shaped sectional form having grooved outer face cap strip portions I8 and' central web portions (Fig. 4). At oppositesides oftheir grooved face portions the cap` strip members are- Aformed with overhanging ilange portions 22; and their web portions 20 are laterally turned as at 24 so as to stiifen the cap strip -members against lateral deflection.

The recessed face portions I8 and the overhanging iiange portions 22 of the cap strip members provide laterally recessed cavity formatiors at the outer faces of the cap strip members into which the fabric covering material 25 of the airfoil is adapted to be tucked and locked by means of locking strips 26. The locking strips 26 are of sheet metal or'the like and the opposite edge portions thereof are adapted to :maintain the fabric 25 withinthe recessed portions of the 'cap strip members and to engage beneath the overhanging flange portions 22 thereof so as to prevent the fabric 25 from becoming disengaged from the cap strip members. It will be understood that thelocking strips 26 may be inserted `in fabric locking arrangement by rst bending the lockingV strips for passage between the overhanging flange portions and then flattening the locking-strips'into flange engaging position.

Intermediately of their ends the cap strip members It-iare relatively braced and interconnected by means of` clip plates 30 which are formed with laterally turned ange portions 32 connected to the web portions 2li-2li of the cor-y responding cap strip members lli-i6, as indilcated at 33. To accommodate the clip plates 30 in close abutting relation thereagainst, the web portions 20-20 of thev corresponding cap strip embers |4-l 6 are laterally turned at their port ons 24-24 away from the clip plates 30 (Fig-4) In the region of the connection of each rib unit I0 withthe trailing edge piece l2, the cap strip elements of each rib unit are directly interconnected by means of rivets or screws or the like as indicated at 35 (Fig. 2). For this purpose the web portions 20-20 of the corresponding. cap strip elements are arranged in relatively lapping relation at their extreme trailing end.

portions, and are cut away as indicated at 36 so as to reduce the depth of the web portions thereat to permit the fabric attachment face portions thereof to converge in accord with the desired streamline edge form of the airfoil. Also, to accommodate the nesting arrangement o f the trailing end portions-of each pair of cap Vstrip elements, the turned portion 24 of one of the web portions 20 thereof is terminated as indicated at 38 just prior to the region of intersection of the paired cap strip members. At their .extreme trailing end portions, the cap strip members I4-I 6 are formed without web portions, and the cap portions thereof are bent at 39 (Fig. 2) to converge into contiguous abutting relationship at their extreme end portions 40. The fabric locking plate devices 26 are arranged to terminate forwardly of the trailing end portions of the rib members, as at 42. ,Key p1ates 44. of wedge shapedsectional form are tted withinS the recessed portions of the cap strip end portions 39-40, and are so dimensioned and shaped as to ll the recessedA portions of the rib elements so as to provide flush outer surfaces. It will be understood that the key plates 44 may -be formed of any suitable metal stock of the approximate sectional form illustrated in Fig. 3,

relation with respect to the rear end portions of the corresponding fabric locking plates 26, as at 46. Thus, the fabric covering portions which are -in line with the fabric locking plates 26 and the ,key plates 44 which are solidly wedged Within the corresponding grooved portions of the rib elements as explained hereinabove. Rivets or screws or the like as indicated at l) are driven through the trailing edge piece l2 and the enclosed portions of the key plates and of the cap strip elements so as to lock the structural elements of the airfoil framing structure together in the form of an integral structure.

It will be particularly noted that because the trailing end portions 40 of the cap Vstrip elements are deformed to lie in contiguous parallel relation, and because the key plates 44 ill the grooved portions thereat, the connection devices 50 may be conveniently provided of riveted form under so-called flat riveting conditions. That is, the hammer and anvil portions of the riveting tool will thereby be enabled to operate against solidly backed dat or parallel faces, and consequently the riveting process will carry on under ideal conditions and an ideally riveted product is 0btainable. It will be notedthat the airfoil covering fabric spans the retracted converging portions of the cap strip members in the region of the connections 50, due to tautening of the'fabric 25 when it is applied to the airfoil framing structure in accord with usual fabric covering practice. Thus any extending head portions of the connection devices 50 avoid interference with assumption ofthe ideal contour form by the fabric 25, and the outer contour of the airfoil when completed is of smoothly converging or knife edge form throughout the airfoil section and in the region of the trailing edge portion thereof. As indicated at 54 (Fig. 3) the forward edge portions of the opposed side walls of the trailing edge piece I2 may be drawn together by means of fasteners 54 intermediately of the regions of connections with the rib elements I0, for stiffening of the trailing edge piece l2.` will be appreciated that this will not interefere with the smoothly rounded rear edge form of the trailing edge piece I2, because the deflections assumed by the trailing edge piece member will be limited to the forward or formerly flat side wall portions thereof.

each comprising a pair of reversely disposed rib lelements converging into connection at the trailments in the regions of said contiguous portions thereof, a trailing edge member of generally U-shaped sectional form mounted to enclose upon said contiguous rib portions and sald'ller plates, and fasteners extending through said trailing edge member and said filler plates and said contiguous, rib portions to provide a rigidly connected frame structure.

2. An airfoil construction comprising, in combination, a metal frame and-a fabric covering mounted thereover, said frame including spaced rib units each comprising a pair of reversely disposed rib elements 4converging into connection at the trailing edge portion of said frame, said rib elements being key-shape grooved at their outer face portions, the end portions of said rib members inthe region of said trailing edge portion having ller plates wedgedly mounted within the grooved portions thereof and being deformed`so that adjacent portions of paired rib elements are contiguous, a sheet metal trailing edge member of generally U-shaped sectional form mounted to enclose upon said congrooved rib element portions and extending into locked relation with said rib elements at opposite sides of the grooved portions thereof. y

3. An airfoil frame including spacedv rib units each comprising a pair of reversely disposed rib elements converging into connection at the trailing edge portion of..said frame, said rib elements being key-shape grooved at their outer face portions, the rear end portions of said rib members being deformed so that adjacent portions of paired rib elements are contiguous, ller plates wedgedly mounted within the grooved face portions of said rib -elements in the regions of said Thus a mechanically simple and rugged fram-v ing and covering structure is provided whereby an airfoil of improved form may befurnished in accord with 'simplied manufacturing procedure. It will be understood that although only one form of the invention has been shown and described in detail 'it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

1. An airfoil frame including spaced rib units contiguous portions thereof, a trailing edge meinber of generally U-shaped sectional form mounted transversely thereof to enclose upon said contiguous rib portions and said 1111er plates, and

fasteners'extending through said trailing edge member and said filler plates and said contiguous rib portions toprovide a rigidly connected frame structure. I

4. An airfoil frame including spaced rib units each comprising a pair of reversely disposed n'b elements converging into connection at the trailing edge portion of said framasaid rib elements comprising cap portions and web portions so as to be of T-shaped section form and having their web portions lapped and interconnected by fastener means located adjacent the trailing edge portion of said frame, the cap portions of said rib elements being key-shape grooved at their outer face portions, the rear end portions of said rib members being deformed so that the cap portions of paired rib elements are contiguous, filler plates wedgedly mounted within the grooved facev portions of said rib elements in the regions of said contiguous portions thereof, a trailing edge member of generally U-shaped sectional form mounted to enclose upon said contiguous rib portions and said filler plates, and fasteners extending through said trailing edge member and said filler plates and said contiguous rib portions toprovide a rigidly connected frame structure, said trailing edge member being deformed into substantially tubular sectional form intermediately of the positions of said rib units.

5. An airfoil frame including spacedrib units each comprising a pair of reversely disposed rib elements converging into connection at the ltrailing edge portion of said frame, said rib elements comprising cap portions and web portions so as to be of T-shaped section form and having their web portions lapped and interconnected by fastener means located adjacent the trailing edge portion of said frame, the cap portions of'said `rib elements being key-shape grooved at their outer face portions, the rear end portions of said rib members being deformed so that the cap por- .tions of paired rib elements are contiguous, the

web portions of paired rib elements being laterally bent in similar direction, brace plates disposed against unbent side portions of said web portions and connected thereto by fasteners, filler plates wedgedly mounted within the grooved face portions of said rib elements in the regions of said contiguous portions thereof, a trailing edge member of generally U-shaped sectional form mounted to enclose upon said contiguous rib portions and said filler plates, and .fasteners extending through said trailing edge member and said filler plates and said contiguous ribportions to provide a rigidly connected frame structure.

6.I An airfoil construction comprising, in combination, a metal frame and a fabric covering mounted thereover,v said frame including spaced rib units each comprising a pair of reversely disposed rib elements converging into connection at the trailing edge portion of said frame, said rib Y elements being key-shape grooved at their outer face portions, the rear, end portions of said rib members being deformed so that adjacent portions of paired-rib elements are contiguous, ller plates wedgedly mounted within the grooved face portions of said rib elements in the regions of said contiguous portions thereof, a trailing edge member of generally U-shaped sectional form mounted transversely thereof to enclose upon said 5 contiguous rib portions and said filler plates, and fasteners extending through said trailing edge member and said filler plates and said contiguous rib portions to providea rigidly connected frame structure, said fabric covering being mounted upon said frame so as to enclose the latter while being folded about said trailing edge member and disposed againstthe outer face portions of said rib members and tucked into said grooved face portions thereof, and sheet metal locking strips superposed upon said fabric in the regions of said grooved rib element portions and extending into locked relation with said rib elements at opposite sides of the grooved portions thereof.

7. An airfoil construction comprising, in combination, a metal frame and a fabric covering mounted thereover, said frame including spaced ribunits each comprising a pair of reversely disposed rib elements converging into connection at the trailing edge portion of said frame, said rib elements comprising cap portions and web portions so as to be of T-shaped `section form and having their web portions lapped and interconnected by fastener means located adjacent the trailing edge portion of said frame, the cap portions of said rib elements being key-shape grooved at their outer face portions, the rear end portions of said rib members being deformed so that the cap portions of paired rib elements are contiguous, the web portions of paired rib elements being laterally bent in similar direction, brace plates disposed against unbent side portions of said web portions and connected thereto by fasteners, ller plates wedgedly mounted within the grooved face portions of said rib elements in the regions of said contiguous portions thereof, a trailingedge member of generally U-shaped sectional form mounted to enclose upon said contiguous rib portions and said filler plates, and fasteners extending through said trailing edge member and said ller plates and said contiguous rib portions to provide a rigidly connected frame structure, said fabric covering being mounted upon said frame so as to enclose the latter while being folded about said trailing edge member and disposed againstl the outer face portions of said rib members and tucked into the grooved cap portions thereof, vand sheet metal locking strips superposed upon said fabric in the regions of said grooved cap portions and extending into locked relation with said cap members at opposite sides of the grooved portions thereof.

GERALD A. W'EINGARTNER. 

